The analysis of the relativistic uniform system in the framework of the covariant theory of gravitation leads to five different masses of the physical system, in which the particles are bound together by means of the electromagnetic and gravitational fields, the acceleration field and the pressure field. In this case it turns out that the systems gravitational mass is equal to the sum of the invariant masses of all the systems particles, and the system’s inertial mass is less than the gravitational mass by the value of the system’s binding mass-energy.